Personally I would use JB for anything in contact with the motor casing. Its higher temperature rating helps it keep its specifications under the increased temperature there.

I use West Systems 105/206 (slow set) for everything else. It is what I have so it is what I use. Never let me down along the way to L3 or Mach 1.8 yet. There are some other epoxies that are slightly stronger but harder to source, so I stick with WS (no pun intended). It is a bit slow sometimes, but working the joint in hot weather with faster hardeners can be stressful.

Generally the quicker the set the less strength the joint has. It is a bit of a generalisation, but generally right. As I said earlier, the data sheet is king in this area. Remember you need to mix them correctly to achieve the specifications. I mix by weight exclusively.

I concur with the comments by OTT.5 minute epoxy will work, but generally speaking, epoxies with longer set times are usually better - primarily due to the different hardener (the part "B") and the resulting structure of the cross-linked polymer.I believe 5 minute Araldite becomes more brittle over time, so I would avoid it (although I did use it in one of my mid-power rockets for convenience)

"Pub, ah yes. A meeting place where people attempt to achieve advanced states of mental incompetence by the repeated consumption of fermented vegetable drinks" (“Timeslides”)

For an L1 rocket (unless you are doing a glass tip to tip or rolling your own tube) all you really need is "hobby" epoxy like BSI. Blake sells this in the Aus rocketry shop. I tend to use either the 15 min or 30 min stuff to make sure I have enough working time.

JB weld is great for anything attached to the motor mount tube (retainer, CR) but to be honest, you could get away with not using it. A small HPR motor will not get hot enough for long enough for you to really need it...but having said that, I always use it for these applications

‘It takes sixty-five thousand errors before you are qualified to make a rocket.’ — Werhner von BraunTRA 12286 L3 TAP member

Hi,Continuing this thread....(might help others)RE: 4" KatanaI've just purchased some J-B Weld for the gluing of the fins (root of fins) to the Motor Mount. This seems like the most sensible decision based on the knowledge that the motor mount will increase in temperature some what. It should also be relatively easy to apply as well.

External FilletsMy decision on the external fillets is West Systems - 105/206/403. That seems like a widely used combination and I like the idea of the 'peanut butter consistency' ... to make the creation of the fillets easier.

Internal FilletsFor the internal Fillets, I was originally toying with idea of using just 24hr Araldite. But now I'm thinking I should just use West Systems instead.In terms of creation of fillets, I wouldn't expect either to be harder to create.

So then it comes down to strength...It looks like there are a lot of different ways to 'measure' the strength of a material.... and it isn't just the strength of material, but the adhesive properties, the temperature of use, etc. Lap Shear strength seems to be a common way to measure the strength...but it is hard to validate and come to any sensible conclusion.

I know that Araldite strength drops off considerably above 100 degrees C. Does that makes me wonder if West Systems 105/206 retains greater strength as temperatures increase. Searched in vain for something to help me compare to Araldite, but nothing solid.Question: Does anyone have any information on West Systems strength at various temperatures?

Any other thoughts?

Cheers

Joep.s. I'm also aware that the surface preparation is KEY to the success of the joint and may significantly affect performance.

I figure it's worth chiming in as it seems everyone has their own preferred epoxy systems. For me, I routinely use 4 different types of adhesives for my builds. This has recently changed as well so it's good to document when changes occur.

1. JB Weld - for Motor Retainers/bonding metal to a motor mount. That's ALL I use it for. Motor retainers.2. Araldite (5 minute) - I use this for tacking fins on as it's fast. 3. Epiglue - for fin fillets and any internal glue work. The consistency is so thick runs aren't a worry. Great stuff.4. Araldite K3600 - I use this for rolling airframes, making fin stock, and doing layups on fins. Incredibly low viscosity so it's great for this type of work.

Historically I used Proline 4500 for fillets and internal work but I went through two quart sets and wanted to go local. I've got some RocketPoxy too but I've never really taken to it. I still have a large amount of Wests Systems but I prefer to use the Araldite K3600 kit given its superior capabilities when compared to Wests.

Proline 4500 for me ,fillets and mechanical bonds (had a rocket driven over by DFWM agricultural vehicle last season ,fillets and bond held)JB weld for retainer bonding ,and that's all it's good for ,my humble opinion.And yeh as Drew said

Hi,Thread is a bit old, but thought I'd just share a small bit about my experiences.

I've been practicing using WS 105/206/403 to help produce the optimum 'mix' for the external fillets. I've used a sieve to filter out the clumps of 403 and I very carefully stir in the 403, being careful not to introduce air into the mix. (Cavitation). So the process of making a good batch takes a while, but 206 is good for up to about 25 mins from memory.

So far, I've had good results with doweling/sandpaper to get the smooth finish. i.e. little or no craters and a good profile.

I've been practicing the process and intend on doing a bit more practicing before I do the real thing. I think have a few practice runs is a very good idea if you don't do it all the time.

I'm up to the internal fillet stage and I'm still finalising the exact strategy/steps. Will definitely be using a syringe and West Systems.

I've already done trial internal fillets on a 'test fin' in an artificial setting, where I could easily put some wooden stops to stop the 105/206 from spilling over the ends of the pretend fins.

Now, with the real thing, access is a lot more constrained, so I'm probably going to push up 5 min epoxy soaked 'stop' (a short stub of rope)...and let it dry there. This to be done at both end of the fins. Then was going to add 105/206/403 (with a viscosity approaching mayonnaise) since I don't really trust the stub to stop pure 105/206 from flowing around. I've seen how the stuff runs. Now I'm pretty sure the 105/206/403 can be made sufficiently runny to fill all the gaps (including the scoring I did of the fins) AND cover as much of the fins/motor mount WITHOUT seeping past the 'block'. i.e. I'm aware that I need to cover as much area as possible to get maximum adhesion. And I have no reason to believe the 403 will reduce the strength of the final epoxy mix.

I don't see much mention by others of the use of 403 in Internal fillets and I must say that makes me wonder why. It seems like an obvious choice. I've already confirmed I can pretty easily push a mayonnaise consistency epoxy mix through tube and syringe.

Personally I would not use west systems because of the viscosity. It's my understanding that anything you add to the epoxy will weaken it to some degree. To me west is more practical for rolling tubes or doing tip to tip.

Generally an internal fillet is not terribly critical so I would normally just be going with a cheap bob smith 15 min epoxy. If I wanted high strength fillet I would go with epiglue.